This paper draws on those elements of our research that investigate the work cultures of inspection, the professional socialization and values that are embedded in practices of inspection, and the background and training of the inspectorate in England and Scotland. Drawing on official documentation and interviews, we present analysis of the background, training, experience and ‘assumptive worlds’ of each national Inspectorate, including their networks, the extent to which they constitute a ‘policy community’ or an ‘elite’; the balance of lay and professional membership, their claims to expertise (especially whether these reside in ‘judgment’ or ‘evidence’), and the extent of commercial, agency involvement in training and management of the inspection workforce. This contributes to a comparative study of the cultures and values of inspection in England and Scotland, with a focus on the kinds of professional knowledge that are mobilised by inspection in the two systems.